Container end closure

ABSTRACT

An end closure for applying to metal containers which is characterized by a central or main panel having a marginal extension terminating in an inwardly curled portion on the peripheral edge of a seaming panel which seaming panel extends inwardly to a chuck-engaging panel portion, and a protective coating of lacquer on the inside face of the closure which extends at least to the chuck-engaging panel portion and provides an area of bare metal for receiving a seaming compound on at least a portion of the seaming panel.

United States Patent Burton L. Gamble Hinsdale, 111.

Aug. 29, 1968 v N Division of Ser. No. 456,213, May 17, 1965, Pat. No. 3,419,418 Apr. 27, 1971 Continental Can Company, Inc. New York, NY.

Inventor Appl. No. Filed Patented Assignee CONTAINER END CLOSURE 1 Claim, 9 Drawing Fig.

us. c1. 220/67, 29/190, 215/40, 220/68 1111.01. 865d 7/42 Field 6: Search 220/62, 64, 66, 67, 68; 215/39, 40; 229/56; 29/190 [56] References Cited UNITED STATES PATENTS 1,328,937 1/1920 Wilbur (220/68UX) 2,102,208 12/1937 Kronquest (220/64UX) 2,548,305 4/1951 Gora (2 l 5/40UX) 3,344,093 9/1967 Strickman 215/40X 3,115,987 12/ 1 963 Bamstead 220/64 Primary Examiner.loseph R. Leclair Assistant ExaminerJames R. Garrett Attorney-Greist, Lockwood, Greenawalt & Dewey FL L H PATENTED M27 1971 sum 1 BF 3 PATENTED mm I97! SHEET 3 OF 3 CONTAINER END CLOSURE This application is a division of US. Pat. application Ser. No. 456,213, filed May 17, 1965, now US. Pat. No. 3,419,418.

It has long been the practice in the manufacture of metal can ends to cut large metal sheets of a suitable thickness into a plurality of strips of predetermined width which are then fed individually to a punch press for cutting and properly die shaping can ends from the strips. In order to effect a substantial reduction in the amount of waste metal resulting from the cutting and punching operations scroll cutting has been developed. This enables the sheets to be punched with the rows of punch holes staggered on the large sheets so that each punch hole in a given row is centered between two punch hole centers in an adjacent row thereby permitting the row centers to be brought closer together but leaving one hole center at the end of each row spaced a substantial distance from the normally straight edge of the sheet. The wastage which would otherwise result from this procedure is further reduced by first scroll cutting the opposite side edges of the large sheet to eliminate most of the waste areas at opposite ends of succeeding rows and then turning the sheet 90 and feeding it step-bystep through scroll shears which cut the sheet transversely so as to divide it into the individual strips which can be fed to the punch presses for cutting therefrom the end closures with a minimum of waste resulting.

- lt is necessary or desirable in most can making operations to apply a protective coating of lacquer or comparable material to the face of the metal which forms the inside can surface. The common practice has been to provide this coating on the metal sheets from which the can blanks are punched after they have been severed from coil stock. The application of the protective lacquer or similar material has been accomplished generally by laying on a relatively thick film of the coating material over the entire surface of the large sheet including the waste areas separating the end closure blanks which result when the end closures are cut therefrom. It has long been recognized that considerable savings in cost would result if a satisfactory procedure could be devised which would enable the application of the coating material to be controlled so that it would not be applied to the portions of the sheet which subsequently become waste and also so as to deposit the coating uniformly and with a thickness sufficient to insure that highly objectionable thin spots or bare spots will not occur while at the same time the necessity for applying an excessively thick coat of the material in order to insure that a coat of adequate thickness is applied to all areas, is avoided.

Various methods and equipment have been proposed for coating the sheet materials so as to accomplish the desired placement and to obtain a uniform coating of the desired thickness but none of the procedures heretofore attempted have proven satisfactory. It has been proposed to spot coat the sheets so that each end closure blank which is subsequently punched from the sheet would have a coated area of a predetermined size and thickness properly placed thereon. However, available equipment generally considered to be suitable for printing on metal sheets has been found to be inadequate either because of an inability to handle the coating materials so as to provide the desired uniformity in placement and thickness of film or because of other problems resulting from the nature of the materials involved. Conventional printing rolls heretofore available of rubber or other similar resilient materials and also metal rolls having a printing surface of normal hardness have been found unsatisfactory because the metal sheets, particularly, when scroll cut, frequently have burrs which dig into the surface of the printing roll and damage the printing surface so as to result in defects in the printing or the depressions in the roll surface cause undesirable registry of succeeding sheets. Also, it has been found that slivers of metal frequently remained on the sheets after the cutting operations and became embedded in the printing surfaces so as to result in objectionable bare spots in the coated areas. Coating rolls having surfaces of soft rubber, particularly, have proven unsatisfactory because some of the coating material is frequently squeezed onto the leading edge of the metal sheet and spills over onto the backup or impression roll which is usually steel or other material providing a 5 hard surface and it becomes necessary to wash or otherwise clean the surface of the impression roll at frequent intervals in order to avoid dirty backs which are objectionable on the printed sheets. When soft surface impression rolls have been employed, as in printing with a hard surface printing roll, it has been found that there is excessive sheet deflection and poor flowout. Also, it has been found that when a soft impression roll is employed and a sheet is fed which is not perfectly flat the soft impression roll will not flatten it sufficiently against the hard surface of the printing roll to obtain acceptable deposit of the coating. A steel or other hard surface impression roll has not been found satisfactory when printing with a hard surface printing roll because it does not compensate for variations which occur in the thickness of the sheet material.

A general object of the invention is to provide a method and apparatus for applying coating materials to thin metal sheets suitable for production of can ends without the aforementioned disadvantages and so as to afford a satisfactory solution to the problems heretofore encountered in previous attempts to apply a uniform coating in the desired areas only with provision for controlling the thickness of the coating in a satisfactory manner.

It is a more specific object of the invention to provide a method and apparatus for spot coating thin metal sheets which are adapted for the production of can ends wherein the placement of the coating areas is accurately controlled so as to eliminate waste of the coating material which otherwise oc curs when the coating material is applied to the entire surface of the sheet and with provision for maintaining accurate control of the thickness of the coating applied to the areas of the sheet to be coated and for reducing to a minimum defects resulting from damage to the surface of the printing roll due to contact therewith of burrs on the metal sheets or slivers clinging thereto as a result of cutting operations prior to the coating operation.

lt is another object of the invention to provide a method and apparatus for applying spot coating to thin metal sheets which are adapted for the production of can ends wherein the desired spot pattern is engraved on a special intaglio printing roll, the roll is mounted in a coating or printing machine with a cooperating impression cylinder mounted for reciprocation so that it may be separated from the engraved roller when a sheet is missing, the sheets being fed to the printing roll after they have been vacuumized to remove any slivers or other foreign material from the surface to be coated.

It is a still further object of the invention to provide a method and apparatus for spot coating thin metal sheets which are adapted to be subsequently divided into strips for feeding to a can end closure forming punch wherein a special intaglio printing roll is employed which comprises a stool shell having a relatively hard copper plating of substantial thickness in which the desired spot pattern is engraved and which is subsequently treated to provide a very thin hard chrome coating over the printing surface after the etching of the pattern therein.

Another object of the invention is to provide an improved can end closure and an'improved method and apparatus which is adapted to be employed in fabricating the closure from thin metal sheets of a suitable metal.

These and other objects and advantages of the invention will be apparent from a description of the improved can end closure and the preferred method and apparatus employed in producing the same which are illustrated in the accompanying drawings wherein:

FIG. 1 is a plan view illustrating a scrolled metal sheet which is to be coated in accordance with the invention;

FIG. 2 is an enlarged fragmentary plan view showing a portion of the sheet of FlG. 1 coated in accordance with the invention;

FIG. 3 is a view of the coating roll with portions of the surface broken away;

FIG. 4 is a fragmentary section of the coating roll, taken on an axial plane and to an enlarged scale, which illustrates the coating roll construction;

FIG. 5 is a longitudinal sectional view, partly diagrammatic, illustrating an apparatus suitable for carrying out the invention;

FIG. 6 is a partial side elevation of the machine, the view showing the far side of the machine as it is positioned in FIG. 5, the direction of travel of the sheets being opposite that of FIG. 5;

FIG. 7 is a fragmentary plan view, taken on the line 7-7 of FIG. 6, to a larger scale;

FIG. 8 is a diagrammatic view illustrating particularly the controls employed in operating the apparatus of FIG. 5; and

FIG. 9 is a fragmentary perspective, to an enlarged scale, showing a portion of a can end closure prepared in accordance with the invention.

Referring first to FIG. I, there is illustrated a scrolled sheet 10 of thin metal which is to be coated in accordance with the invention. The sheet 10 is generally formed by feeding a continuous strip or web of metal of suitable thickness for forming can ends from asupply coil and scroll shear cutting the web transversely to form individual sheet lengths as shown at 10. In this manner sheets are provided with scroll cut end edges arranged in parallel relation and presenting alternating projections 11 and recesses 12, the center of each projection 11 at a given end of the sheet being in line with the center of the recess 12 at the opposite end of the sheet in the manner shown in FIG. 1. After the scroll sheets of FIG. I are formed, they may be fed to a coating apparatus for applying thereto a lacquer or other suitable coating as hereinafter described. After the sheets I0 are coated and baked, they are fed to a scroll shear for cutting across the same on the scroll lines I4 so as to divide the sheet into a plurality of scroll strips 15 which are adapted to be fed individually and lengthwise thereof to the punch and die equipment which punch can closure ends therefrom on the lines indicated at 16 in FIG. I. By staggering the rows of punch cuts and scroll cutting the sheet and strip edges a minimum of waste or scrap results.

As shown in FIG. 2 of the drawings, the protective or decorative coating of lacquer or the like is applied to the scroll sheet in FIG. I in the form of spots indicated at 17 which are approximately centered within the punch lines 16 and with the diameter thereof substantially smaller than the diameter of the punch line so as to leave an uncoated margin inside the punch line and also to leave the areas between the punch lines 16 without any coating. This provides an uncoated area indicated at 18 in FIG. 9 which is adapted to receive the seaming compound 20 employed in forming the double seam when the can end is applied to a can body. It will be apparent by comparison of FIGS. 1 and 2 of the drawings, that by coating the axes or spots I7 with accurate placement of the spots, substantial portions of the sheet which do not require coating are left without the coating and a minimum of coating material is employed. The uncoated areas outside the punch lines 16 are waste and a saving in material is effected by omitting the coating in these areas. It has been found desirable to leave an area inside the punch line 16 uncoated because the seaming compound has a greater adherence to the uncoated metal than to the coated portions thereof. This area is included in the seam when the can closure is applied to the can body so that it is necessary only that the coating spot 17 extend into the area which receives the seaming compound a sufficient distance to insure that' no bare metal is exposed on the inside of the completed can after the closure is applied.

In the coating of the scroll sheets I0 in the manner herein described, a coating roll such as shown in FIGS. 3 and 4 of the drawings, is employed. The coating roll is of special construction. It includes a shaft 26 surrounded by a core or shell 27 which is of a hard metal such as steel and on the periphery of which there is applied a copper plating 28 of greater than normal hardness. The copper plating is applied by a process of electrodeposition which produces a hardness substantially greater than the normal hardness of plated copper, the latter generally having a Knoop hardness ranging from to I00. Preferably, the copper sheath, indicated at 28 in FIG. 4, has a Knoop hardness in the neighborhood of 200. The thickness of the copper plating 28 is made sufficient so that it is about 0.006 to 0.008 inch greater than the depth of the cells when the roll is etched to apply a screen pattern on the desired coating or printing areas. The desired spot pattern, indicated at 30 in FIG. 3, is etched into the hard copper plating 28 by conventional methods using a screen pattern with the size and spacing of the etched cells adapted to be varied to obtain the thickness desired in the particular area, thereby affording control of the thickness of the coating so that it may be varied, as desired, in any portion of the coating spots 17. A relatively thin or light coating or plating 29 of chrome is applied to the etched roll when the etching is completed, the thickness of the chrome being in the neighborhood of 0.0002 to 0.0003 inch. The chrome is, of course, very hardand adheres well to the copper so that it provides a very good wear surface.

A suitable apparatus-which may be employed for engaging the coating roll surface with the scrolled sheets in proper registry in a manner herein described is illustrated in FIGS. 5 to 7. The preferred printing or coating apparatus 30 is of the general type described in US. Pat. No. 2,623,495 to Johnson, issued Dec. 30, I952, and US. Pat. No. 1,848,856 to Wagner et al., issued Mar. 8, I932, to which reference may be had for details not hereinafter described. In the apparatus which is illustrated, the coating roll or printing cylinder 25 is rotatably supported in relatively fixed position in an upright frame by suitable bearings in vertically disposed, generally parallel side frame members 32. The applicator roll or printing roll 25 is vertically aligned above a cooperating impression roller 33 which is carried on a shaft 34 joumaled at its ends in bearing members carried in a supporting frame 35 which is pivotally mounted as hereinafter described.

The impression roll 33 comprises a metal core or shell having mounted on the cylindrical surface thereof a sheath or blanket of rubberlike composition material 36. The composition sheath 36 should have sufiicient flexibility to compensate for variations in the thickness of the sheet material while at the same time it should be hard enough to flatten the sheet against the hard surface of the printing roll as it advances between the printing roll 25 and the roller 33 so as to obtain acceptable transfer of the coating material from the printing areas onto the surface of the sheet. An impression roll having a surface with a hardness in the neighborhood of 80 to durometer has been found satisfactory for cooperation with the printing roll 25. The sheath 36 is held on the core or shell of the roll 33 by a conventional plate lockup or clamp device 37 so that a surface gap of predetermined dimensions results.

The impression roll supporting frame 35 carries the impression roll 33 at one end and is pivotally mounted at its other end for swinging movement about the axis of the pivot shaft 38. Upwardly extending adjustable posts 40 are pivotally connected at 41 to the sides of the frame 35 and have pivotal connections at their lower ends with toggle arms 42 mounted upon a cross shaft 43, the latter having a lever arm 44 pivotally connected at the free end at 45 to the free end of the piston rod 46 extending from an operating cylinder 47. The cylinder 47 is pivotally mounted at 48 on a bracket forming part of the framework 31. In this manner, the impression roll 33 may be raised and lowered by operation of the air cylinder 47 so as to engage and disengage the printing roll 25. The operation of the air cylinder is controlled as hereinafter described.

The coating material is supplied to the printing or coating roll 25 through a supply pipe 49 having axially spaced discharge perforations permitting discharge of the coating material onto the roll 25 above a doctor blade 50 which is mounted on a bracket plate 5I depending from a cross shaft 52. The cross shaft 52 is mounted in sliding relation in suitable bearings in the side frame structures 32 and is provided with a mechanism for imparting thereto an axially reciprocating movement which comprises an eccentric 53 mounted on the upper end of the vertically disposed output shaft 54 of a right angle drive device 55 and having a connecting link pivotally connected with the end of the shaft 52 so that rotation of the eccentric results in axial reciprocation of the shaft 52. The right angle drive device 55 has a sprocket 57 on its input shaft connected by chain 58 with a sprocket 59 on the driven cross shaft 60. A self-locking worm 61, mounted at the end of the shaft 52, is turned by the hand wheel 63 and engages a worm gear 64 on the shaft 52 so as to adjust the pressure of the blade 50 against the printing roll 25. The supporting plate 51 is angled so as to cooperate with the roll 25 to form a fountain for the coating material. A doctor blade or wiper blade mechanism, indicated at 65, is mounted at each end of the roll 25 to wipe the roll ends clear of the coating material. Suitable collecting receptacles indicated at 66 are mounted on the side frames 32 below the doctor blades 50 and 65 with connecting conduits for returning the collected coating materials to the supply line.

The sheets are fed into the coating machine by hand or by any other means and forwarded on the top run of an elongate feed conveyor 67 (FIG. 5) which is mounted at its ends on sprockets 68 and 68' supported on suitable transverse shafts 69 and 69' joumaled in suitable hearings on an elongate feed table 70 which includes guide devices for the sheets and the conveyor 67. The sheets are pushed by sheet engaging fingers 71 on the conveyor 67, and advanced toward the coating and impression rollers 25 and 33. A relatively short feed conveyor 72 is mounted at the inner end of the conveyor 67 on end sprockets 73 and 73' carried on transverse shafts 74 and 74'. The conveyor 72 has L-shaped sheet engaging fingers 75 pivotally mounted and cam track controlled which take over the advance of the sheets from the fingers 71 of the conveyor :67 and advance the successive sheets between a pair of pinch rolls 76 and 77 at the entrance to the coating and impression rollers 25 and 33. The conveyor 72 is run somewhat faster than the conveyor 67 and the sheet engaging fingers 75 are controlled by the cam tracks so that the sheet engaging surface of the finger 75 is maintained vertical while in engagement with the trailing edge of a sheet as the finger travels along the top run of the conveyor 72 and also as it moves down around the leading end of the conveyor, permitting accurate timing of the sheet advance and smooth engagement and release of the sheet. The conveyor 67 may be driven in a conventional manner, by a suitable drive train, such as illustrated at 78, from the power shaft 80. Since the drive train 78 is entirely conventional it will not be explained in detail.

The pinch rolls 76 and 77 are operated to take over the advance of the sheet from the conveyor 72 after the leading edge of the sheet has reached the coating and impression rollers 25 and 33. The uppermost pinch roll 76 is mounted in relatively fixed position on a cross shaft 82 with a conventional spring cam follower rollers 91 are held by tension springs 92 and the cam plates 90 are, of course, constructed so as to properly time the engagement and disengagement of the lowermost pinch roll 77 with the uppermost roll 76 and the takeover of the control of the sheet movement between the coating and impression rollers 25 and 33. A driven magnetic roll 93 mounted on a cross shaft 94 is spaced in advance of the coating and impression rollers 25 and 33, and cooperates with the pinch rolls 76 and 77 to advance the sheet and control its movement during the application of the coating and to discharge the coated sheet from the machine.

' pressure applying apparatus, indicated at 83, which is adjusta- The various driven elements of the machine are powered by suitable drive connections with the power shaft (FIGS. 5 and 6) which may be connected to a motor orother power source. A pinion 96 (FIG. 6) on the shaft 80 engages gear 97 on the cross shaft 60 to drive the shaft 60. The coating roll 25 is driven from the shaft 60 by a gear train including connecting gears 98, 99, 100, 101 and 102. The impression roller 33 carries a sprocket 103 which is driven by chain 104 and sprocket 105 on a shaft concentric with pivot shaft 38 and having at its one end a gear 106 engaging gear 107 on a shaft 108. A gear 110, on the shaft 108, engages gear 111 which is mounted concentric with gear 101. The upper pinch roll 76 and magnetic roller 93 are driven by suitable gear trains indicated at 112 and 113 from the gear 101.

The machine includes an arrangement for retracting the impression roller 33 in the event no sheet is fed to receive the coating. The impression roller 33 is held in an up" position as long as sheets are fed in succession and the operation of the conveyor 72 is timed to advance successive sheets so that the leading edge of each sheet enters between the impression roller 33 and the coating roll 25 in proper relationship with the etched surface pattern so that the coating material is applied at the proper location on the sheet and none of the coating is applied to the surface of the impression roll. A sheet sensing device 115 (FIGS. 5 and 8) is located in the table 70 and connected into an electrical control circuit for operating an air valve, indicated at 116, in FIG. 8, controlling the air cylinder 47 through a time delay relay device indicated at 117. When a sheet is missing the sensing device 115 signals the relay device 117 and the valve 116 is operated in proper timed relation to the rotation of the coating and impression rollers 25 and 33 to retract the latter so that none of the coating material is deposited on the surface of the impression roller due to the absence of a sheet.

The sheets to be coated are scroll cut and then thoroughly cleaned to remove any dirt, metal slivers or other foreign particles. As indicated in FIG. 8, the sheets are passed beneath a brush 121, a vacuum device 122 and a second brush 123 for cleaning the same. The cleaning may, of course, be done prior to feeding the sheets to the coating machine. They may be fed to the machine by hand or by automatic means onto the main infeed conveyor 67, with the associated feed conveyor 72 timed to deliver successive sheets to the coating and impression rollers 25 and 33. The sheets are picked up by the pinch rolls 76 and 77 and advanced between the coating and impression rollers 25 and 33 and to the magnetic roll 93 for delivery out of the machine. Subsequent baking operations dry the coating material and the sheets are then cut into strips for the punching operations to produce the can end closures.

The closure forming shell or blank which is punched from the coated sheet is shaped by the punches, as shown in FIG. 9, in preparation for application to the open mouth or end of the container by the end applying and seaming machines. The shell or blank comprises a main or central end panel portion 125 which is surrounded by a chuck wall portion 126, which is in turn surrounded by a seaming panel portion 127, with a seaming panel radius portion 128 connecting the same, and a curl portion is formed on the outermost edge of the seaming panel portion 127. Prior to the application of the closure blank to the container it is supplied with seaming compound 20 which may be applied as shown so as to extend from the curl 130 to somewhere between three-fourths of the way across the seaming panel 127 and one-half of the way up the seaming panel radius 128 so that the seaming compound overlies portions of the blank which are left free of the coating material and when the double seam is formed the compound is spread into the crevices resulting from the seaming operation. The compound may, of course, be applied in any conventional manner, and it may cover any desired area. The compound is found to have better adherence if applied to the bare metal and the coating need be applied only so that it extends outside the main end panel 125 and into the seam forming area a sufficient distance to insure that no bare metal will be exposed inside the completely closed container.

portion at the radially inner edge of said seaming panel, and said blank having a protective coating of lacquer extending over the center panel on the surface which is to be disposed inside the container which lacquer coating extends to the chuck wall portion and terminates short of the seaming panel and a seaming compound applied to the bare metal area of the annular seaming panel which faces in the same direction as the lacquered surface of the center panel. 

1. A metal closure forming member for application to the mouth of a container comprising a thin metal blank having a closure forming center panel and a marginal portion adapted to be formed into a double seam structure when applied to the container, the blank being shaped to provide in the margin thereof an annular seaming panel of substantial width with a peripheral curl extending in the direction of the surface which is to be disposed inside the container and a chuck wall forming portion at the radially inner edge of said seaming panel, and said blank having a protective coating of lacquer extending over the center panel on the surface which is to be disposed inside the container which lacquer coating extends to the chuck wall portion and terminates short of the seaming Panel and a seaming compound applied to the bare metal area of the annular seaming panel which faces in the same direction as the lacquered surface of the center panel. 